1. Field of the Invention
This invention relates to a mechanism for grasping and releasing workpieces in a manner that prevents accidental damage to the workpieces. It further relates to a mechanism and system for moving workpieces from one location to another during manufacturing. It further relates to such a mechanism and system which are especially adapted for use in moving semiconductor wafers and similar articles which are prone to damage by contamination and which have a relatively high value before manufacturing is completed.
2. Description of the Prior Art
The manufacture of integrated circuits takes place in Class 100 clean environments, either in entire rooms which meet such standards of clean air or in laminar flow hoods which meet such standards. Semiconductor wafers in which the integrated circuits are being fabricated are conventionally loaded into quartz, metal or plastic wafer boats, depending on the process step being performed, and manually moved from one work station to another. However, in such clean environments, human beings are a significant source of contamination. In an effort to reduce human contact with the semiconductor wafers during the fabrication process, it is known to provide laminar flow hoods with closed fronts incorporating flexible gloves into which operators insert their hands to move wafer boats within the laminar flow hoods. However, the use of such flexible glove closed fronts makes the movement of wafer boats filled with semiconductor wafers within the hood a clumsy operation at best.
Another approach that has been incorporated in some integrated circuit manufacturing operations has been to eliminate the use of wafer boats in favor of air slides or similar apparatus for moving the semiconductor wafers from place to place. However, that approach tends to lack flexibility for incorporating different equipment in the manufacturing line. It therefore finds favor only in situations where a very large volume of standard parts is to be fabricated over a substantial period of time. However, the manufacture of integrated circuits is a dynamic business, in which constant change is the norm. There is therefore a further need to improve apparatus for handling semiconductor wafers and similar articles which are prone to damage from contamination. Any mechanisms used for this purpose must themselves not be a source of significant contamination to the environment in which the integrated circuit manufacturing takes place, and it must be capable of picking up wafer boats at one location, moving them to another location, and releasing them, all in a very reliable manner without damaging the valuable product being manipulated.